Typical wireless network systems comprise one or more access devices for communication purposes. The users may be communicated with the access device with personal computers or notebook computers via wireless means. Wireless local area networks (WLANs) were originally intended to allow wireless connections to a wired local area network (LAN), such as where premises wiring systems were nonexistent or inadequate to support conventional wired LANS. WLANs are often used to service mobile computing devices, such as laptop computers and personal digital assistants (PDAs). Typically, Access Points (APs) are set to ensure adequate radio coverage throughout the service area of the WLAN, while minimizing the costs associated with the installation of each AP. The APs must be configured to eliminate coverage gaps and to provide adequate coverage.
A wireless transport network is a network comprises a plurality of wirelessly connected devices that are responsible for relaying traffic for associated mobile clients. An example of a wireless transport network is a plurality of IEEE 802.11 capable devices that provide transport service for IEEE 802.11 or Bluetooth capable clients such as laptop computers, PDA (personal digital assistant), and the like. The network can further comprise one or more connections to a wired network through one or multiple edge devices. The edge devices are equipped and capable of both wireless and wired communication. In a wireless transport network, efficient reduction of unnecessary broadcast traffic is critical. The wireless transmission medium (the air) by nature is shared, therefore broadcast is a convenient way of communication in wireless networks for there is no need to transmit multiple times for a multi-destined frame. Once an originator broadcasts a frame to all its neighboring devices, some, if not all, of its neighboring devices will have to relay the frame for other remote devices. For any device that is a neighbor of multiple devices that are responsible for relaying broadcast frames, it receives multiple copies of the same frame. One simple example is once a device sends out a broadcast frame, it immediately receives multiple copies of the identical frame if there are multiple neighboring devices perform relay function for the frame. Unless a filtering method is implemented on the devices, in the worst case one single broadcast frame may be duplicated in an exponential growth fashion and saturate the network and waste device processing time. In the worst case, these frames may loop around the network until the end of their lives.
As opposed to wired networks, a wireless network has a stronger limitation on available bandwidth therefore the control overhead for route determination has to be low. Wireless network is relatively error-prone therefore the routing method has to be able to work with frame loss from time to time, and to provide resiliency. On the other hand, a wireless network provides shared medium by nature therefore broadcast to neighboring nodes can be achieved easily. Many academic and industrial organizations have been working on various forwarding mechanisms on mobile ad-hoc networks. The topologies in general represent networks that the hosts try to access the network are also responsible for relaying the traffic for the network. An ad-hoc network architecture is a network that can be deployed rapidly without relying on preexisting fixed network infrastructure. The nodes in an ad-hoc network can dynamically join and leave the network as well as being highly mobile. The communication protocols for mobile ad-hoc network emphasizes mobility for all nodes while in a wireless transport network, although the transport topology may still be dynamic, the mobility and roaming capability are for the mobile clients. The prior art includes the following:                U.S. Pat. No. 6,130,881, Stiller, et al., entitled “Traffic routing in small wireless data networks,” Oct. 10, 2000.        U.S. Pat. No. 5,987,011, C. K. Toh, entitled “Routing method for ad-hoc mobile networks,” Nov. 16, 1999.        U.S. Pat. No. 6,304,556, Z. J. Haas, entitled “Routing and mobility management protocols for ad-hoc networks,” Oct. 16, 2001.        U.S. Pat. No. 6,549,786, R. Y. M. Cheung, entitled “Method and apparatus for connecting a wireless LAN to a wired LAN,” Apr. 15, 2003.        Published documents by IETF MANET working group, please refer to http://www.ietf.org/html.charters/manet-charter.html.        
U.S. Pat. No. 6,130,881 claims a method to identify wireless routing devices with N-bit addresses in an N-node wireless network. The main objective of the invention is to minimize forwarding processing overhead in a wireless network with small number of nodes. U.S. Pat. No. 5,987,011 discloses a routing technique for ad-hoc mobile networks that all devices can participate routing. The route paths are constructed under on-demand basis and the path selection is based on the stability of neighboring hosts. Stability of a neighboring node is measured by the number of contiguous “beacons” a host receives from its neighbor. This technique can be used to answer the high mobility requirement for a mobile ad-hoc network. U.S. Pat. No. 6,549,786 teaches the mechanism to set up a plurality of wireless nodes and a plurality of wired-wireless edge access points to form a local area network. The internetworking edge access points are used to relay traffic for wireless nodes unless the source and destination pair can communicate with each other directly. The wireless nodes actively select which access point it should be associated with, and determines whether it needs an AP's help to send messages. This is a one-tier solution and covers only basic connectivity issues. U.S. Pat. No. 6,304,556 discloses two communication protocols for ad-hoc networks. One for routing and the other is for mobility management. The routing protocol is a proactive-reactive hybrid routing protocol that each node is required to proactively learn the full topology of the network within its predefined routing zone, which is represented by a maximum number of hops as the distance. The mobility management protocol relies on some network nodes assuming the management function. Each mobility management node knows the location of all nodes within its zone, and communicates this information to any other mobility management node that requests it. Each node in the network has to associate with one or more management nodes. For a node needs a route to a remote destination, the node reactively queries the selected management node first, and then the management node obtains the information of the destination by communicating with other management nodes, and reply to the query. This technique is a source routing mechanism and it requires all participating nodes to execute the same protocol in the network. Members in IETF MANET working group are working on defining a few experimental routing protocols for mobile ad-hoc networks. The purpose of this working group is to standardize IP routing protocol functionality suitable for wireless routing application within both static and dynamic topologies. Two of its four experimental protocols comprise the concept of “relay nodes” selection. However, the protocols always utilize bi-directional access capability and never consider “link quality” as a routing metric.
The prior art does not teach a method of routing and forwarding techniques for a wireless transport network system based on Layer 2 (link layer) addresses on a multi-hop wireless communication.